Powder compacting press

ABSTRACT

AN ISOSTATIC POWDER PRESS FOR COMPRESSING CERAMIC POWDERS TOGETHER TO FORM A TOILET BOWL SECTION, SAID PRESS INCLUDING ONE OR MORE DEFORMABLE MEMBRANES SUBJECTABLE TO FLUID PRESSURE TO UNIFORMLY COMPRESS THE POWDERS TO A SUBSTANTIALLY CONSTANT DENSITY THROUGHOUT.

United States Patent 3,664,799 POWDER COMPACTING PRESS Claude RollinWallick, Jr., William Edward Blodgett, and Donald Keith Lazor,Louisville, Ky., assignors to American Standard Inc., New York, N.Y.

Filed Nov. 4, 1969, Ser. No. 873,890 Int. Cl. 1328b 3/02 US. Cl. 4253892 Claims ABSTRACT OF THE DISCLOSURE An isostatic powder press forcompressing ceramic powders together to form a toilet bowl section, saidpress including one or more deformable membranes subjectable to fluidpressure to uniformly compress the powders to a substantially constantdensity throughout.

DRAWINGS FIG. 1 is an exploded sectional view of a toilet bowl havingone of its major parts formed by a press of this invention.

FIG. 2 is a sectional view of a mechanism for loading powder into theinvention press.

FIG. 3 is a cross sectional view of a press of the present inventionadapted to form one of the toilet bowl sections shown in FIG. 1.

FIG. 4 is a sectional view of a press constituting another embodiment ofthe invention.

Drawings in greater detail--FIG. 1

FIG. 1 is an exploded view showing a toilet bowl 8 formed of sixseparate but connectable sections numbered 10 through 15. Each sectionmay be formed from ceramic powders or pellets, as for example mixturesof ball clay, china clay and alumina. The powders for each section areloaded into a press and compacted to form a green uncured port of thedesired shape. Thereafter the joinable edges of the various parts aremoistened, and the parts assembled together in a conventional stick-upoperation. The assembly is then dried, glazed and fired, as underconventional practice.

As shown in FIG. 1, the element identified by numeral 13 appears to beformed as part of bowl section 10. Actually element 13 (known aspanplate) is formed separately from bowl section 10, and is later stuckonto section 10 by causing its lateral edges to seat against shoulder 22pre-formed in the bowl section. The panplate is suitably curved, and theshoulders 22 are so configured that the joining edge or crack 23 isobliterated or eliminated in the finished article.

Bowl section 10 is the major section or part of the toilet bowl and isthe most difficult to form under conventional practice. Under thepresent invention the green and uncured bowl section 10 can bepress-formed from powders by means of the press shown in FIG. 3 or 4.Powder may be initially loaded into the press by the mechanism shown inFIG. 2.

FIG. 3

As shown in FIG. 3, the press comprises two separate die mechanisms 25and 27. Mechanism 25 forms the upper interior surfaces of the bowlsection, and mechanism 27 forms the lower undersurfaces of the bowlsection. Each die mechanism includes a supporting steel plate or shell,a rigid core, and a deformable elastomeric membrane. Relative verticalmovement of the two die mechanisms allows them to separate at partingline 26 for removal of the formed article and insertion of the nextpowder charge. Such vertical movement can be accomplished by manual ormechanical means (not shown).

Patented May 23, 1972 Actual formation of the part is accomplished byintroduction of pressure fluid into channels located behind therespective elastomeric membranes; the membranes act as transmitters ofthe fluid pressure to the powder charge.

Die mechanism 25 comprises a flat steel plate 32 having a rigid coremember 34 secured to its upper face. Overlying core 34 is a deformableelastomeric bag or membrane 36 having its peripheral edge area 38 lyingflat against steel plate 32. An annular steel plate 40 is suitablybolted to plate 30 to clamp the peripheral edge of the membrane 36 inplace.

At selected points on its upper surface the core 34 is provided withchannels or grooves 42, said grooves communicating with one or morepassages 44 leading through the steel plate 32. Introduction of pressurefluid to passage 44 from a pressure source (not shown) causes themembrane 36 to be deformed away from the back-up surface of core 34,thus compressing the powders previously admitted to the powder space 46.

Die mechanism 27 comprises a steel shell 48 which encircles and fixedlycontains a rigid die cavity member 50. This die mechanism furthercomprises a plunger assembly 52 which includes a steel plate 54 and arigid core member 56 adhered to plate 54 by any suitable means (notshown). Overlying the exposed surface of core 56 is a second deformableelastomeric membrane 58 having its peripheral edge 60 clamped in placeby means of an annular plate 66. Plate 66 is provided with an endlessperipheral skirt or rib 72, as well as internal ribs 68 and 70, saidribs serving to anchor and confine the adjacent sections of theelastomeric membrane 58 so that said sections are incapable of movementrelative to the plunger assembly 52. The plunger assembly (members 54,56, 58 and 66) is capable of vertical slidable movement through anopening 73 formed in member 50. Normally the plunger assembly ismaintained in the illustrated elevated position by compression springs75; however when it is necessary to eject a formed part the plungerassembly is moved down by application of a downward force on plungersurface 77. Annular retaining ring 49, which is bolted to steel shell48, restrains plunger assembly 52 in the elevated position.

As shown in FIG. 3, the lower face of core 56 is provided with one ormore channels 74 which connect with passages 76 leading through plate54. With the parts in their FIG. 3 positions pressure fluids can besimultaneously introduced into passages 76 and 44, thus causing thechannels 74 and 42 to fill with fluid and produce movements of themembranes 58 and 36 away from the respective core 56 and 34 surfaces.The simultaneous movements of the two membranes 58 and 36 causes themass of powder in cavity 46 to be compressed to the generalconfiguration and thickness denoted by dotted line 78. In general, themovement of each membrane 36 or 58 is in a direction normal to thebackup surface of the respective core. The membranes thus have difierentportions thereof moving in different directions as determined by thecontour of the core sections, so that the membranes function somewhat inthe manner of complex motion dies, but without the mechanicalcomplications or difficulties. The use of multiple membranes as shown inFIG. 3 is therefore advantageous for pressing powders into complexshapes which may have hidden crevices or undercuts therein. Since themembranes move at right angles to the adjacent core surfaces they havedirect compressive action on the powder granules without any substantialtraverse sliding contact between the adjacent powder particles orbetween the powder particles and the membrane surfaces. The generalconfiguration of the article is therefore well preserved, and there islittle tendency for the wall sections to be excessively 3 thinned out inany particular area. Compaction using multiple deformable membranesprovides minimum average particle movement for a given degree ofcompaction and therefore provides uniform density in the final product,thus contributing to maximum strength without requirement for excessivewall thickness.

Ejection of the compacted article from the die cavity is accomplishedafter the die mechanisms 25 and 27 have been separated from one anotherat parting line 26. Mechanism 27 can be drawn up from mechanism 25and/or mechanism 25 can be drawn down from mechanism 27 by suitablemeans, not shown. With the two die mechanisms thus separated from oneanother a downward force can be applied to plunger surface 77 to movethe plunger downward through opening 73, thereby ejecting the compactedarticle 78 from the press cavity.

It will be noted from FIG. 3 that the end edges 82 and 84 of the toiletbowl section are formed by machined surfaces on members 40, 68, 70 and72. These edges 82 and 84 are the upper and lower edges of the FIG. 1bowl section which are to be joined to the bowl sections 12 and 14,respectively; they should therefore be fairly flat, without ridges ordepressions, if they are to correctly mate. By forming edges 82 and 84on machined surfaces the edges are not likely to be wavy, hilly, etc.due to any variations in fluid supply pressure, elastomer durometer,elastomer thickness, etc.

It is of some importance that the planar outline of the compactedarticle be maintained Within fairly close dimensional tolerances,especially the peripheral outline of the article immediately adjacentthe bowl section lower edge 84. Thus is because the surface area ofsections 10 and 14 must be continued uninterrupted to eliminateobjectionable cracks or joints in the finished article. The FIG. 3compacting apparatus is designed so that wall surface areas at andadjacent to edge 84 are formed by rigid cavity surfaces which aredimensionally stable and which are the same irrespective of any minorvariations in deformation of member 74 during the application of fluidpressure through passages 76 and 44.

FIG. 2powder loading FIG. 2 schematically illustrates one mechanism forloading powder onto membrane 36. The loading operation is performed withthe upper die section removed from the lower die section 25, so that theupper face of membrane 36 is exposed to receive powder thereon. Thepowder is initially delivered from a hopper 90 which seats on a powderbox 92. Box 92 has a lower surface 94 configured to the same shape asthe face of membrane 58 when said membrane is in its normal unstressedstate as shown in FIG. 3. Box 92 is preferably provided with one or morepassages 96 which communicate between a manifold space 98 and respectiveporous metal filters 100 disposed at selected points on surface 94.

Application of a vacuum to manifold 98, coupled with the suddenapplication of a substantial volume of gas from gaseous pressure pump 99to space 102, causes the powder in hopper 90 to be fluidized, and todischarge rapidly into the space 104 to produce a lightly compactedpowder layer on the surface of membrane 36. After removal of box 92 fromdie mechanism 25 it is intended that the lightly compacted powder layeradhere to the elastomeric membrane 36 rather than to box surface 94. Ifnecessary the powder layer can be prevented from adhereing to the boxsurface 94 by previous application of powdered mold release agents tosurface 94; also a positive gas pressure can be produced in manifold 98,

to act through passages 96 to thus eject the powder preform away fromsurface 94.

FIG. 4 press FIG. 4 shows a press generally similar to the FIG. 3 pressexcept that the upper deformable membrane 58 has been omitted. Insteadthe lower face of plunger 52 acts as a fixed die surface.

The principal feature of the present invention is the construction ofthe die mechanisms shown in FIGS. 3 and 4, whereby the single ormultiple deformable members 36 and 58 are utilized to heavily compactthe powder material in a manner to produce a green ware article havingclosely toleranced dimensions and uniform density.

We claim:

1. An isostatic powder press for compressing a toilet bowl section whichis to be later joined with other bowl sections at its upper and lowerperipheral end edges: said press comprising first and second diemechanisms advanceable toward each other to define a powder cavity, andretractable from each other to permit discharge of the formed toiletbowl section; said first die mechanism comprising a rigid cavity membercontoured to form the external undersurface 0f the bowl section, a firstcentral rigid core section, and a first deformable membrane shaped toform the interior undersurfaces of the bowl section; said first membranelying against said first rigid core section and having its peripheraledge sealed thereto; said first core section having fluid passagestherein for admitting pressure fluid to the dead space between themembrane and the core section; said second die mechanism comprising asecond convex core section locatable within the space circumscribed bythe first die mechanism, and a second deformable membrane shaped to formthe interior upper surfaces of the bowl section; said second membranelying against the second core section and having its peripheral edgesealed thereto, and said second core section having fluid passagestherein for admitting pressure fluid to the dead space between thesecond membrane and second core section, whereby when both dead spacesare pressurized the membranes are deformed toward one another tocompress the powder.

2. The powder press of claim 1 wherein the first die mechanism comprisestwo relatively movable parts, one of said parts being the aforementionedrigid cavity member, and the other part being a plunger element slidablyreceived in a central opening of the rigid cavity member for ejection ofa pressed powder bowl section from the cavity; said plunger elementincluding the aforementioned first rigid core section and theaforementioned first deformable membrane.

References Cited UNITED STATES PATENTS 3,041,685 7/1962 Taccone 164170 X3,238,576 3/1966 Taccone 164-170 X 3,156,958 11/1964 Miller et a1 1641703,172,153 3/1965 Lodmis et al. 1,177,240 3/1916 Gates.

.I. SPENCER OVERHOLSER, Primary Examiner B. D. TOBOR, Assistant ExaminerU.S. Cl. X.R.

